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Manual 2100-522B
Page 29 of 38
All three phase scroll compressors used in the Q-T
EC
series are wired identically internally. As a result, once
the correct phasing is determined for a specific system
or installation, connecting properly phased power leads
to the same Fusite terminal should maintain proper
rotation direction. The direction of rotation of the
motor may be changed by reversing any two line
connections to the unit.
COMPRESSOR CONTROL MODULE
The compressor control module is standard on all
models covered by this manual. The compressor
control is an anti-short cycle/lockout timer with high
and low pressure switch monitoring and alarm relay
output.
Adjustable Delay On Make And Break Timer
On initial power up or any time power is interrupted to
the unit, the delay on make period begins, which will be
2 minutes plus 10% of the delay on break setting.
When the delay on make is complete and the high
pressure switch (and low pressure switch if employed)
is closed, the compressor contactor is energized.
Upon shutdown the delay or break timer starts and
prevents restart until the delay on break and delay on
make periods have expired.
During routine operation of the unit with no power
interruptions the compressor will operate on demand
with no delay.
High Pressure Switch and Lockout Sequence
If the high pressure switch opens, the compressor
contactor will de-energize immediately. The lockout
timer will go into a soft lockout and stay in soft lockout
until the high pressure switch closes
and the delay on
break time has expired. If the high pressure switch
opens again in this same operating cycle the unit will
go into manual lockout condition and the alarm relay
circuit will energize. Recycling the wall thermostat
resets the manual lockout.
Low Pressure Switch, Bypass, and Lockout
Sequence
If the low pressure switch opens for more than 120
seconds, the compressor contactor will de-energize and
go into a soft lockout. Regardless the state of the low
pressure switch, the contactor will reenergize after the
delay on make time delay has expired. If the low
pressure switch remains open, or opens again for longer
than 120 seconds the unit will go into manual lockout
condition and the alarm relay circuit will energize.
Recycling the wall thermostat resets the manual
lockout.
Alarm Relay Output
Alarm terminal is output connection for applications
where alarm relay is employed. This terminal is
powered whenever compressor is locked out due to HPC
or LPC sequences as described.
NOTE: Both high and low pressure switch controls are
inherently automatic reset devices. The high
pressure switch and low pressure switch cut out
and cut in settings are fixed by specific air
conditioner or heat pump unit model. The
lockout features, both soft and manual, are a
function of the Compressor Control Module.
ADJUSTMENTS
Adjustable Delay on Make and Delay on Break
Timer
The potentiometer is used to select Delay on Break time
from 30 seconds to 5 minutes. Delay on Make (DOM)
timing on power-up and after power interruptions is
equal to 2 minutes plus 10% of Delay on Break (DOB)
setting:
0.5 minute (30 seconds) DOB = 123 second DOM
1.0 minute (60 seconds) DOB = 126 second DOM
2.0 minute (120 seconds) DOB = 132 second DOM
3.0 minute (180 seconds) DOB = 138 second DOM
4.0 minute (240 seconds) DOB = 144 second DOM
5.0 minute (300 seconds) DOB = 150 second DOM
During routine operation of the unit with no power
interruptions the compressor will operate on demand
with no delay.
Typical Settings for Dual Unit Installation:
Unit 1: DOB set at 2 minutes, and DOM is 132 seconds
Unit 2: DOB set at 4 minutes, and DOM is 144 seconds
SERVICE HINTS
1. Caution user to maintain clean air filters at all
times. Also, not to needlessly close off supply air
registers. This may reduce airflow through the
system, which shortens equipment service life as
well as increasing operating costs and noise
levels.
2. Check all power fuses or circuit breakers to be
sure they are the correct rating.
3. Periodic cleaning of the outdoor coil to permit
full and unrestricted airflow circulation is
essential.